A system in which a user connects to a network such as the Internet using a terminal device such as a personal computer and obtains information through a web page provided by a server device or the like has been conventionally used. Since there are enormous amounts of web pages on the Internet, for example the user searches for information by using a search service and the like and efficiently locates interesting information based on search results. This search service uses a search engine for executing a search process based on a search word or the like entered by the user, and generates a list of web pages relevant to an object of the user's interest to generate a search result page.
Meanwhile, web pages are also very useful as advertising media. In particular, the search service is a service frequently used by the user, and displaying on the search result page has significant advertisement effects. Furthermore, by displaying an advertisement relevant to the search word entered by the user, it is possible to efficiently present the advertisement to the user who is a potential customer.
As an example of a method for easily displaying such an advertisement, there is a method whereby information about a web site of an advertiser is included in a list of search results. Here, the advertiser registers a keyword and the like associated with a search word beforehand so that its advertisement is displayed on a search result page when a search is performed based on the search word associated with the keyword. In detail, a system in which a plurality of advertisers bid for a predetermined keyword and display advertisements according to these bids is used. It is believed that a higher ranking in the search result list for the search word entered by the user calls more attention of the user who performs the search. In view of this, for example, a system in which rankings in the search result list displayed in the search result page are determined according to bid amounts of the advertisers is proposed (as an example, see Japanese Patent No. 3676999 (hereafter referred to as patent document 1)).
However, the system of patent document 1 merely determines the rankings in the search result list in decreasing order of bid amount and displays the advertisements in the search result page according to the rankings. On the other hand, an advertiser may desire various display forms depending on, for instance, budget or public relations activities. For example, the advertiser may want to display the advertisement in association with a lot of keywords at a low price even in a small space, or may want to display the advertisement prominently in a larger space rather than simply displaying it at the top. Moreover, the advertiser may want to display the advertisement at a specific ranking (for example, second or third) or position. Furthermore, the advertiser may want to display the advertisement intensively for a short period of time in accordance with a specific date and time such as an opening day or an inventory clearance day. In these cases, in the system of patent document 1, the advertiser may not be able to display such an advertisement that is suited to its budget or public relations activities. For example, the ranking changes in relation to the bid amounts of the other advertisers in the system of patent document 1. This being so, even when the advertiser wants to display the advertisement continuously at the same ranking or position in the web page, such a desire of the advertiser is unable to be satisfied.
Besides, in the case where many advertisers want to display their advertisements at a specific ranking or position, the following problem arises. In a typical auction, it is impossible to bid without a bid amount that exceeds a highest bid amount. Meanwhile, an advertisement is not displayed for an indefinite period of time, and it is expected that the placement of the advertisement has a time limit as in the case where the advertisement ends after a predetermined advertisement placement period, the advertisement ends with a predetermined number of clicks as an upper limit, or the advertisement ends with a predetermined charge amount as an upper limit. In such a case where the placement of the advertisement has a time limit, though it is impossible to successfully bid with the current bid amount, once the current advertisement ends, it becomes possible to successfully bid even with a bid amount not higher than the current bid amount or a bid amount below the current bid amount. There may be an advertiser that does not intend to bid with the current bid amount due to its budget and the like, but is willing to bid once the advertisement of the current bid amount ends.
This being the case, it is inconvenient for both the advertiser and the server operator if the currently bid advertisement frame is unable to be bid without a bid amount exceeding the current bid amount. In other words, the advertiser misses a good opportunity to advertise with a relatively low bid amount, and the server operator has a problem of the advertisement frame being left unsold after the currently displayed advertisement ends, until the next advertiser appears.